How to I list applications sorted by modified time in Finder on OS X 10.8?

Solution 1:

The view your screenshot displays can be produced if you go to the View menu and select Arrange by ▸ Name (or press ^⌘1). When "Arrange by Name" is selected, indeed changing the sort order is not possible. If, however, you select View then Arrange by ▸ None or press ^⌘0, your problem is solved.

Solution 2:

Go to View Menu > Arrange By > None. That will make the columns editable. You can sort by whatever criteria you want now.

Solution 3:

On the top of the Finder window, you have a set of buttons called View. Right beside that is a button called Arrange with a drop down arrow. Click the arrow and you can arrange however you want: by name, date, etc.